What is problematic in the case of such a semiconductor device is that a lack of adhesion between a substrate and the plastic housing composition enables moisture to accumulate in the boundary layer between substrate and plastic housing composition. Said moisture expands abruptly if the semiconductor device is heated from room temperature to temperatures up to 260° C. within a very short time during soldering onto a printed circuit board. The abrupt expansion of the moisture content results in cracks and/or fractures in the plastic housing of the semiconductor device, which is referred to as the “popcorn effect”.
In order to prevent this popcorn effect, it is necessary to prevent the accumulation of moisture in the boundary layer between semiconductor device components and plastic housing composition. The accumulation of moisture can be reduced by improving the adhesion between the surfaces of the semiconductor device components and the surface of the plastic housing composition. Various approaches are known for improving said adhesion. U.S. Pat. No. 5,554,569 discloses a method for mechanically roughening the surface of a leadframe. The roughened surface enables intermeshing with the plastic housing composition and hence better adhesion. However, this method is difficult and cost-intensive to carry out. Moreover, this method cannot be employed on all substrates, nor on the active top side of a flip-chip.
Particularly in the case of semiconductor devices embodied using flip-chip technology, the problem additionally occurs that from the soldering of the semiconductor chip onto the substrate, corrosive residues of soldering resist are present between the semiconductor chip and the substrate, which can damage the device and/or additionally reduce the adhesion of the plastic housing composition.
Therefore, there is still a need for a semiconductor device whose semiconductor device components have a reliable adhesion to a plastic housing composition surrounding them.